Add new file

kunst/js/index.js

+const queryInput = document.getElementById("query");
+const h4Elements = document.querySelectorAll(".maincontent h3");
+
+queryInput.addEventListener("input", () => {
+  const query = queryInput.value.toLowerCase();
+
+  h4Elements.forEach((h4) => {
+    const h4Text = h4.textContent.toLowerCase();
+    if (h4Text.includes(query)) {
+      h4.parentNode.style.display = "block";
+    } else {
+      h4.parentNode.style.display = "none";
+    }
+  });
+});